Most of the methods identified here are part of typical site investigation work for any construction project that is dependent on ground conditions. Soil sampling requires boreholes or pits for the retrieval of samples but these represent small areas of disturbance relative to the ground surface traversed by most utility projects. Soil sampling also can be combined with groundwater monitoring to determine groundwater levels and geochemical conditions that might affect the structural design and corrosion protection required for the utility being installed or the rehabilitation being planned. Important aspects of planning and design information can be collected from analysis of existing local records and prior projects in the vicinity. An important category of non-invasive site investigation techniques involves geophysical survey methods. In addition to finding buried objects (as discussed under asset location), these methods can identify boundaries among soil and rock zones and infer some aspects of the geotechnical properties of those zones.